Conventionally, power is supplied to the on-board electrical system of a motor vehicle using a generator.
In addition, at least two generators are used to supply energy to the electrical system of certain vehicles, for example security vehicles, emergency vehicles, and utility vehicles, in order to ensure that the required power and/or reliability of the electrical supply can be provided.
The wear, and thus also the life span, of a generator depends on several factors. One of these factors is its electrical loading. The higher the electrical load of a generator is, the greater is its wear, and the lower its remaining life span. It is therefore desirable, in devices for providing the supply voltage for the loads of a vehicle electrical system using a plurality of generators, to make sure that the degree of loading of the generators used is equal.
German Patent No. DE 41 08 861 describes a device having generators connected in parallel. In this conventional device, a voltage regulator is allocated to each of the generators. In addition, this device has at least one battery of which one terminal can be connected to the voltage regulator via an ignition switch. In addition, a charge control device is provided that is connected to the ignition switch and to the voltage regulators, and that can be connected via a switching device to the negative terminal of the battery, which is preferably at ground. Between the charge control device, the voltage regulators, and the named switching device, there is a circuit system having a plurality of components that are conductive in one direction and are blocking in one direction. This device is intended to achieve the effect that through the use of two generators a high degree of electrical power can be produced, and that errors that may occur in one of the two generator-voltage regulator systems can be indicated using a single indicator device, for example a charge control lamp, it being possible for the other generator-voltage regulator system to continue to operate without problems.